Portable devices, such as mobile or cellular telephones, are often equipped with a headset. The headset includes a microphone and one or two speakers. The headset further includes a push-button switch electrically connected across the microphone, and which may be used, for example, to “wake-up” the phone. A detection circuit is needed to reliably detect closure of the push-button switch, which detection circuit must not interfere with the normal operation of the microphone 112 other than when the button is depressed.
It is also advantageous to provide such a detection circuit which does not unnecessarily consume power. Preferably the detection circuit should be able to remain active for long periods of time with very low power consumption.
Accordingly, what is needed in the art is a better way to detect the state of a switch. More specifically, what is needed in the art is a less power consumptive way to detect whether or not a push-button is depressed.